The present invention is directed to a printing unit including at least first and second printing pairs or couples. A satellite cylinder cooperates with a transfer cylinder of the first pair. A drive assembly is provided for the cylinders.
A printing press is known from EP 0 644 048 B1 in which pairs of cylinders, each consisting of a forme cylinder and a transfer cylinder, are mechanically fixedly coupled. Each cylinder pair has its own drive motor. The cylinder pairs themselves cannot be coupled to each other.
DE 44 30 693 A1 discloses printing units of a printing press with separate configurations of cylinders which are driven individually, or in groups. Cylinders, or groups of cylinders, are not in a driven connection with each other.
A four-cylinder printing unit is known from DE 196 03 663 A1. The two transfer cylinders which cooperate with each other are fixedly coupled to each other and can be selectively driven by the drive mechanism of one or of both associated forme cylinders. In one embodiment, a pair of cylinders, consisting of a forme cylinder and a transfer cylinder, which can be driven at the forme cylinder, can be placed against this four-cylinder printing unit, and can be coupled into the drive linkage between the two first mentioned transfer cylinders for synchronization, or to attain correctly registered printing.
EP 0 997 273 A2 discloses a four-cylinder printing unit, in which the four cylinders can be driven by two drive motors. Two couplings at the journals of the two forme cylinders, and two gear wheels, which can be axially displaced on the journals of the two transfer cylinders, facilitate the formation of different drive linkages.
WO 00/06384 A1 discloses printing units with satellite cylinders in a modular construction which make possible a multitude of production possibilities by use of flexible arrangements. Each satellite cylinder has its own drive motor or can be coupled to one of the cooperating cylinder pairs.
The object of the present invention is directed to providing a printing unit.
In accordance with the present invention, this object is attained by the provision of a printing unit having a first cylinder pair comprised of a first forme cylinder and a first transfer cylinder. A second cylinder pair is also provided and is comprised of a second forme cylinder and a second transfer cylinder. A satellite cylinder, together with the transfer cylinders, forms a printing location. A drive for the first forme cylinder, and a drive for the first transfer cylinder form a coupled drive linkage which, during printing is driven by a common drive motor on the transfer cylinder. A drive mechanism for the satellite cylinder can be selectively switched and coupled, through a first coupling, with the drive linkage of the first cylinder pair. With the coupling engaged, the drive is taken off the drive motor and transferred to the satellite cylinder.
The advantages which can be gained by the present invention lie, in particular, in that a large operational diversity and variability of a printing unit or of compound cylinders, together with a high degree of operational dependability, is provided by redundancy, without each cylinder being provided with its own drive mechanism. The present invention unites the advantages of the high degree of flexibility provided by the expensive and elaborate single drive technology with the advantages of coupled cylinder groups, namely the savings of motors and the mechanical synchronization of the connected cylinders.
As a rule, by the optimized arrangement of switchable couplings and motors, as many of the desired operating modes are possible as would be provided with an embodiment where all cylinders are provided with separate motors. Thus, with the coupling released, it is possible to move cylinders, or groups of cylinders, independently of each other, which movement is required, for example, when the printing formes or rubber blankets are exchanged, when a paper web is drawn in, or when rollers and cylinders are independently inked or washed. In many cases, an auxiliary drive mechanism can therefore be omitted, since the function of this auxiliary drive mechanism can be taken over by the main drive mechanisms, if the couplings are appropriately switched. In the same way, is it possible to perform the switching of individual cylinders or cylinder groups of connected larger cylinders, in that new drive linkages are formed by releasing couplings and activating other couplings.
Moreover, a substantial advantage lies in the option of standardizing individual small groups, for example a pair of cylinders consisting of a forme cylinder and a transfer cylinder with an appropriate coupling, and of combining them in any desired way, in response to a request made in a purchase order, into larger units. An above discussed pair of cylinders can also represent a standard group, together with a counter-pressure cylinder. The journals of the cylinders can be embodied as needed, for example selectively, with or without coupling, with a gear wheel which is fixed against relative rotation or can be fixed in place, matching a first or second drive level.
In a preferred embodiment, the transfer cylinder of the pair is driven. In this way, it is possible to definitely define a flow of moments up to an inking unit, which aids in improving the printing quality.
In particular, in connection with printing units which can be switched from rubber-on-rubber to rubber-on steel operation, i.e. in which at least one of the transfer cylinders can be selectively placed against a counter-pressure cylinder or against a second transfer cylinder, a reversal of the direction of rotation of one or several cylinders is necessary, depending on the printing unit, and thus requires the release of drive linkages and the formation of new drive linkages. With a five-cylinder printing unit, an embodiment with one drive motor for each pair of forme and transfer cylinders is advantageous, and in which the counter-pressure cylinder can be coupled with one of the two drive motors, or with both drive motors, or with cylinder pairs, depending on the paper guidance and the mode of operation.
In such embodiments, a flying plate exchange is possible for a five-cylinder printing unit by use of only two drive motors and only two couplings. This can be accomplished without the need for auxiliary drives for subsequent cylinder acceleration or for appropriate devices for circumferential registration changes and/or for finding the register, which are typically necessary prior to recoupling.
A one-sided printing forme change is possible in an embodiment with only one drive motor and with only two couplings, for example, for preparing an imprint.
An embodiment, in the form of a four-cylinder printing unit expanded by a further cylinder pair, for example, is advantageous for a six-cylinder y- or lambda-printing unit, which can be flexibly employed, for example, for a 2/1 production run, for the flying one-sided plate change, or during the imprint function in the course of 1/1 printing.
The present invention can also be employed particularly advantageously and efficiently in seven-cylinder, nine-cylinder or ten-cylinder printing units, when maximum flexibility, together with a minimal number of motors, is required.
In the situation of several pairs of cylinders working together directly or via a counter-pressure cylinder, there is the possibility of changing the relative rotational position of the forme cylinders with respect to each other, for example for the adjustment of the circumferential or ink registration, by uncoupling.
The great operational dependability provided by the present invention, because of the redundancy in the number of usable drive motors, which provides a so-called back-up function, is also particularly advantageous in the situation of several drive mechanisms which can by connected by couplings.